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blockdev: handle ZFS dataset sources in list_dev_by_dir #2138

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blockdev: handle ZFS dataset sources in list_dev_by_dir #2138

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31 changes: 30 additions & 1 deletion crates/blockdev/src/blockdev.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -382,10 +382,39 @@ pub fn list_dev(dev: &Utf8Path) -> Result<Device> {
.ok_or_else(|| anyhow!("no device output from lsblk for {dev}"))
}

#[context("Finding block device for ZFS dataset {dataset}")]
fn list_dev_for_zfs_dataset(dataset: &str) -> Result<Device> {
let dataset = dataset.strip_prefix("ZFS=").unwrap_or(dataset);
let pool = dataset
.split('/')
.next()
.ok_or_else(|| anyhow!("Invalid ZFS dataset: {dataset}"))?;
Comment on lines +388 to +391
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@gemini-code-assist gemini-code-assist bot Apr 11, 2026

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medium

The split('/').next() call on a string will always return Some (even for an empty string), making the ok_or_else block unreachable. Furthermore, if the dataset string is empty or only contains the ZFS= prefix, pool will be an empty string, which will cause the zpool command to fail later. It's safer to filter out empty strings to ensure a valid pool name is extracted.

Suggested change
let pool = dataset
.split('/')
.next()
.ok_or_else(|| anyhow!("Invalid ZFS dataset: {dataset}"))?;
let pool = dataset
.split('/')
.next()
.filter(|s| !s.is_empty())
.ok_or_else(|| anyhow!("Invalid ZFS dataset: {dataset}"))?;


let output = Command::new("zpool")
.args(["list", "-H", "-v", "-P", pool])
.run_get_string()
.with_context(|| format!("Querying ZFS pool {pool}"))?;

for line in output.lines() {
if line.starts_with('\t') || line.starts_with(' ') {
let dev_path = line.trim_start().split('\t').next().unwrap_or("").trim();
if dev_path.starts_with('/') {
return list_dev(Utf8Path::new(dev_path));
}
}
}

anyhow::bail!("Could not find a block device backing ZFS pool {pool}")
}

/// List the device containing the filesystem mounted at the given directory.
pub fn list_dev_by_dir(dir: &Dir) -> Result<Device> {
let fsinfo = bootc_mount::inspect_filesystem_of_dir(dir)?;
list_dev(&Utf8PathBuf::from(&fsinfo.source))
let source = &fsinfo.source;
if fsinfo.fstype == "zfs" || (!source.starts_with('/') && source.contains('/')) {
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medium

The heuristic (!source.starts_with('/') && source.contains('/')) is too broad and will incorrectly match network filesystems like NFS (e.g., server:/export). This would cause bootc to attempt running zpool on non-ZFS systems, which might fail if the zpool command is missing or the source is not a valid pool. It is recommended to rely primarily on fsinfo.fstype == "zfs" or a more specific prefix like ZFS=.

Suggested change
if fsinfo.fstype == "zfs" || (!source.starts_with('/') && source.contains('/')) {
if fsinfo.fstype == "zfs" || source.starts_with("ZFS=") {

return list_dev_for_zfs_dataset(source);
}
list_dev(&Utf8PathBuf::from(source))
}

pub struct LoopbackDevice {
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